Electronic tube



May 19, 1936. G. SOLOMON ELECTRONIC TUBE Filed May 29, 1935 INVENTOR5mllermaflozomolz BY WMou/ ATTORNEY WITNESSES Patented May 19, 1936EJITED STATES PATENT OFFICE ELECTRONIC TUBE Application May 29,

2 Claims.

This invention relates to electronic tubes, and more specifically toelectronic tubes of the type that are used in radio detectors andamplifiers.

It is an object of this invention to provide an improved electronic tubewhich may be used in radio detection and amplification and which will besubstantially free from the troublesome outside interference caused bystatic or the discharge from high frequency machines and spark gaps.

A further object is the provision of an improved type of shielding forradio tubes which will be economical to manufacture, which will occupy aminimum of space, and which will not interfere with the proper operationof the tube.

With these and other objects in mind, reference should be had to theaccompanying drawing, in which:

Fig. 1 is an elevation of an electronic tube embodying the presentinvention; and

Fig. 2 is a sectional view in the direction of the arrows on the line 22of Fig. 1.

In the accompanying drawing my invention is illustrated as applied to avacuum electronic tube of a conventional type which is quite frequentlyused in radio receivers and comprises a suitable glass casing orenvelope l enclosing the op erative elements of the tube and secured atits lower end to a base portion ll made of dielectric material.

Supported in a glass stud l2 projected upwardly inside the tube are aseries of posts [3 to which are secured the plate [4, the two portionsl5 and I6 of a screen grid, and a control grid I1. Also supported in theglass stud I 2 are the cathode I8 and the heating filament I9. Extendingthrough the base of the tube are a plurality of prongs 20 adapted to befitted into a suitable socket. Two of the prongs are connected to thetwo ends of the filament l9, another prong is connected to one portionof the screen grid I6, another to the plate l4, while the fifth prong isconnected to the control grid 11. The two portions of the screen grid 15and iii are secured together in conventional manner as by a metal diskor plate attached over the upper end of the elements. A wire 2|extending through the top of the tube and connecting with a contactmember 22 is connected to the cathode l8.

While the tube herein shown and described is one type of electronic tubeto which my invention may be applied, it is to be understood that it maybe used in association with any desired type of electronic tube.

To protect the operative elements of the tube from outside interferencedue to static or to the operation of high frequency machines or sparkgaps, I encase the operative elements of the tube 1935, Serial No.24,148

in an improved type of shield disposed inside of the glass casing orenvelope It. My improved shield is composed of an outer layer of metalfoil 24 made of a good conducting material, and an inner layer ofinsulating material such as the sheet of dielectric paper 25, which arewrapped around the plate, grid, cathode and filament of the tube so thatthey overlap as at 26 and are suitably secured together at the upper endas by the twisted wire 21. The lower end is tightly tied around theupper end of the glass stud I2 as by another strip of wire 28, which ispreferably provided with a lead 29 extending through the glass stud l2and connecting with a prong 30 which projects through the base of thetube.

The prong 30, when the tube is in use, is con nected to a suitableground 3| so as to cause all interference entering the tube to begrounded. To insure a good electrical contact between the lead wire 29and the foil 24 a solder connection may be employed. The wire 2! passesthrough the upper end of the wrapping or shield in such a manner as notto contact the layer of foil 24 but to be insulated therefrom by thepaper 25.

An electronic tube embodying a shield of the type illustrated anddescribed herein will be substantially free from outside interference inthat all static and stray electrons will be grounded. The provision ofthe shield, however, will not materially increase the cost of producingthe tube nor will it cause the tube to occupy any additional space in aradio set.

Of course, it is to be understood thatmy improved type of shielding maybe applied to electronic tubes of other types than the one hereinillustrated and described.

I claim:

1. In an electronic tube, a shield comprising an outer layer of metalfoil and an inner layer of dielectric material disposed inside the tubeand encasing the operative elements thereof, said layer of metal foilbeing connected to a conductor projecting through said tube forconnecting it to a ground.

2. An electronic tube comprising a glass envelope, a base portionsecured to the envelope, electron emitting means, electron receivingmeans, and control means disposed inside of said envelope and havingconnection with a plurality of conductors projecting through the baseportion, and a shield comprising an outer layer of metal foil and aninner layer of dielectric material disposed inside said envelope andencasing said electron emitting, electron receiving and control means,said metal foil having connection with a conductor projecting throughthe base of the tube.

GUILLERMO SOLOMON.

